Info (lost the linkie):
"Zombie bears. Desperate people who need rescuing. The great weapon of Holy Water. A flaming horse called War. A plague of violent weirdness is coming to Rockstar's hit western Red Dead Redemption. The forthcoming Undead Nightmare is infested with it.
John Marston is the hero in Undead Nightmare. In a cut-scene I was shown, he encounters Redemption's creepy gravedigger Seth who is playing cards with an even creepier and nearly motionless zombie named Moses. Marston, still voice-acted by the same guy who did him in Redemption, as are the other returning characters, is incredulous: "I've seen husbands eating wives, mothers eating sons!" He wants to know what's up.
Undead Nightmare looks different from Red Dead Redemption. The color palette is tinged with sickened greens and the skies above its familiar terrain are darkened. Zombies and zombie animals are everywhere. As I rode Marston west on his zombie horse I was distracted by what I thought was one of the new "random events," the zombie versions of the robberies, hunts, and suicides that populated Redemption's west. I never got a chance to find out because I was set upon by zombie animals. Wolves, I think they were. Like zombie people, they were harder to kill then their properly-born counterparts.
The military has established safe zones in Undead Nightmare. In these few places, you need not worry about zombies. Elsewhere, they shamble and march. Towns are taken over. I rode into one where the hordes of undead had forced its surviving citizens to the roof. When reaching such towns, a town safety meter appears atop your TV, shifting toward the positive as you kill zombies or head to the roofs and help arm the survivors. Cleared towns become save points, though they can be overrun again. You won't be able to save in the wilderness in Undead Nightmare. There be zombies.
In Red Dead Redemption there were outlaws to hunt. In Undead Nightmare, there are missing people to rescue. Rockstar let me send Marston toward an icon on the mini-map which represented a big house overrun by the recently un-deceased. The missing person was in the house, anxious for me to clear the zombies and let him on my horse. In this fight, I tested some of Marston's new weapons. Zombies don't shoot guns, but they attack in packs. Against them, the new blunderbuss is a one-shot kill. Holy water is essentially a tossed grenade of zombie-frying potency. Zombie bait is another throwable item with a stink that attracts zombie. Toss bait. Let them gather. Bless them with holy water. Zombie problem solved. Rescued people must be brought back to safe zones.
Undead Nightmare has quests and more "stranger" missions, the latter of which were the intriguing adventures spurred by odd people who popped up in various parts of the Redemption world. Undead has new outfits and hunting challenges as well as the promise of mythical creatures, such as the Four Horses of The Apocalypse: War, Death, Famine and Pestilence, each with special abilities. The score is new, composed by the musicians behind the music of the original game.
Rockstar's Undead Nightmare will run about five hours in single-player and cost $10. It is the first expansion to Red Dead Redemption to primarily offer content for solo players. It will require players to own a copy of Red Dead Redemption, and it will be out just before Halloween."